Tomcat 8, HikariCP, Hibernate and MySQL - mysql

Question

Using a Connection Pool
I am using a Hikari Connection Pool to interact with the MySQl database backend in a Java based Web project. I decided to upgrade the library versions to their most recent stable versions and now I cannot connect to the database anymore.
Java 8
MySQL 5.7
Tomcat 8
Dependencies
I use the following Maven dependencies:
<dependency>
<groupId>com.zaxxer</groupId>
<artifactId>HikariCP</artifactId>
<version>2.4.5</version>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-hikaricp</artifactId>
<version>5.2.0.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>5.2.0.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-envers</artifactId>
<version>5.2.0.Final</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>6.0.2</version>
</dependency>
Hibernate
The project compiles fine, no libraries are missing. This is my hibernate configuration file:
<session-factory>
<property name="hibernate.connection.provider_class">com.zaxxer.hikari.hibernate.HikariConnectionProvider</property>
<property name="hibernate.hikari.dataSourceClassName">com.mysql.jdbc.jdbc2.optional.MysqlDataSource</property>
<property name="hibernate.hikari.dataSource.url">jdbc:mysql://localhost:3306/CitationUserDB?useSSL=false</property>
<property name="hibernate.hikari.dataSource.user">dbUser</property>
<property name="hibernate.hikari.dataSource.password">vErYsEcReT</property>
<property name="hibernate.hikari.dataSource.cachePrepStmts">true</property>
<property name="hibernate.hikari.dataSource.prepStmtCacheSize">250</property>
<property name="hibernate.hikari.dataSource.prepStmtCacheSqlLimit">2048</property>
<property name="hibernate.hikari.dataSource.useServerPrepStmts">true</property>
<mapping class="Database.Authentication.User"/>
</session-factory>
SessionFactory
I use this Hibernate Util class to get the session object.
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
/**
* Hibernate session management
*/
public class HibernateUtilUserAuthentication {
private static SessionFactory sessionFactory;
public static SessionFactory getSessionFactory() {
if (sessionFactory == null) {
// loads configuration and mappings
Configuration configuration = new Configuration().configure("hibernate.userauthentication.cfg.xml");
ServiceRegistry serviceRegistry
= new StandardServiceRegistryBuilder()
.applySettings(configuration.getProperties()).build();
// builds a session factory from the service registry
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
}
return sessionFactory;
}
}
Error
The following error is thrown, when the first database access happens in the source code. There seems to be a problem with the claspath, but all required libraries are there and I can see them in IntelliJ.
Caused by: org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment]
at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:244)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:208)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:189)
at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:51)
at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:94)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:217)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:189)
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.handleTypes(MetadataBuildingProcess.java:352)
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:111)
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.build(MetadataBuildingProcess.java:83)
at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:418)
at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:87)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:691)
at Database.Authentication.HibernateUtilUserAuthentication.getSessionFactory(HibernateUtilUserAuthentication.java:104)
at Database.Authentication.UserAPI.authenticateUser(UserAPI.java:133)
at Database.Authentication.UserAuthentication.login(UserAuthentication.java:60)
at Bean.LoginBean.login(LoginBean.java:94)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.el.parser.AstValue.invoke(AstValue.java:247)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:267)
at com.sun.faces.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:105)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:87)
... 32 more
Caused by: org.hibernate.HibernateException: java.lang.RuntimeException: java.lang.ClassNotFoundException: com.mysql.jdbc.jdbc2.optional.MysqlDataSource
at com.zaxxer.hikari.hibernate.HikariConnectionProvider.configure(HikariConnectionProvider.java:86)
at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:94)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:217)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:189)
at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.buildJdbcConnectionAccess(JdbcEnvironmentInitiator.java:145)
at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:66)
at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35)
at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:88)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:234)
... 56 more
Caused by: java.lang.RuntimeException: java.lang.ClassNotFoundException: com.mysql.jdbc.jdbc2.optional.MysqlDataSource
at com.zaxxer.hikari.util.UtilityElf.createInstance(UtilityElf.java:120)
at com.zaxxer.hikari.pool.PoolUtilities.initializeDataSource(PoolUtilities.java:110)
at com.zaxxer.hikari.pool.BaseHikariPool.<init>(BaseHikariPool.java:157)
at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:60)
at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:48)
at com.zaxxer.hikari.HikariDataSource.<init>(HikariDataSource.java:80)
at com.zaxxer.hikari.hibernate.HikariConnectionProvider.configure(HikariConnectionProvider.java:82)
... 64 more
Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.jdbc2.optional.MysqlDataSource
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1305)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1139)
at com.zaxxer.hikari.util.UtilityElf.createInstance(UtilityElf.java:105)
... 70 more
But the library is there:
It is copied to Tomcat during deployment:
./webapps/Testapplication/WEB-INF/lib/mysql-connector-java-6.0.2.jar
I have no idea why the JDBC MySQL driver cannot be found. Any help is really appreciated.
Thank you in advance!

Answer 1

The package structure has changed in mysql-connector-java-6. Switch to mysql-connector-java-5.x
<!-- http://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.39</version>
</dependency>